We are studying neural mechanisms that relate to and account for auditory sensation and behavior. Our basic interest is how the auditory system is organized to measure and encode cues relevant to certain acoustic phenomena, especially sound localization and pitch. Organizational principles can be revealed through experiments which relate the responses of single neurons (recorded with use of microelectrodes) to binaural acoustic stimuli to their location within auditory nuclei. These binaural stimuli are known to be localized to certain positions in sensational space. The products of such experiments are functional maps that reveal how the spatial organization of the nuclei under study can account for their known functional (behavioral) results. That is, they show how neurons responsive to these binaural stimuli are arrayed within auditory nuclei; and they allow for the production of response-profile maps that reveal the total response within a nucleus arising from given binaural stimuli. It is an objective of these studies to produce such maps for the medial superior olive, central nucleus of the inferior colliculus and for primary and secondary auditory cortical fields in the cat. Organizational principles can also be revealed in anatomical-physiological studies of the projections from level to level in the system. These studies reveal how the response properties of neurons at each level arise as a product of highly-ordered, invariably convergent projections into that level. These results shall be related to known psychoacoustic behavior, especially sound localization, and should provide basic information about how the auditory system is organized to generate these sensational phenomena. BIBLIOGRAPHIC REFERENCES: Roth, G.L., and Merzenich, M.M.: Response properties and distribution of delay-sensitive neurons within the central nucleus of the inferior colliculus of the cat. JASA 51S:54, 1975 (Abstract). Merzenich, M.M., and Colwell, S.A.: Spatially ordered convergent projection from the auditory thalamus to and from A-1 in the cat. JASA 57S:55, 1975 (Abstract).